<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
	<title>测试用</title>
	<style type='text/css'>
		*{
			margin:0;padding:0;
		}
		.wrap {
			width:300px;
			position: relative;
		}
		.aa {
			position: absolute;
			top:0;
			border:1px solid #ccc;
		}
		.top {
			width:300px;
			height:30px;
			text-align: center;
			line-height:30px;
		}
		.cen {
			width:300px;
			height:30px;
			text-align: center;
			height:100px;
			display: none;
		}
	</style>
</head>
<body>
	<div class='wrap'>
		<div class='aa'>
			<div class='top'>
				sssssssss
			</div>
			<div class='cen'>
				2222222222
			</div>
		</div>
	</div>
</body>
</html>